Circuit interrupter



Jan. 14, 1936. R. M. DAVIS CIRCUIT INTERRUPTER Filed Jan. 25, 1934 2 Sheets-Sheet 1 INVENTOR Robe/" Mm/Zs.

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Patented Jan. 14, 1936 UNITED STATES PATENTv OFFICE aoz'mzi cmcnrr INT1-:naman of Pennsylvania Application January z3, 1934, serial No. 107,920

16 Claims.

My invention relates to an improved means for indicating the rating of electrical apparatus, and is particularly applicable to circuit breakers of the type wherein interchangeable trip devices are used for altering the normal current rating there- In the past, it has been the general practice of the manufacturers of circuit breakers to market a separate design of breakermechanism and trip device for each particular rating. In the interests of economy, itis desirable to standardize and consolidate these many designs into as few as possible. One method of accomplishing this is to provide unitary interchangeable trip devices which are used with a single closure, operating mechanism, and contact structure. This arrangement eliminates the necessity of carrying large stocks of breakers, but has not been free from certain diiliculties.

Perhaps the most troublesome of these dliilculties has been the provision of means whereby the rating of the trip device in use with the breaker' could be made visible from the outside of the breaker closure. Various arrangements for accomplishing this have been proposed and tried. One that has been widely used is the engraving of the outside of the closure itself following the installation of the trip device. This, however', is expensive, requires considerable time when an order is being filled, and necessitates a new closure if the trip device is replaced with one of differing rating. Likewise, the other methods such as painting the rating on the outside of the circuit breaker closure, have not satisfactorily solved the problem.

It is, therefore, an object of my invention to provide an improved means whereby the rating of a removable, interchangeable trip device for use with circuit breakers shall be visible from the outside of the breaker closure, and at the same time shall always be correct even though the trip device may have been changed.

` Another object of my invention is to provide a rating indicating means of the above described type that shall comprise a means integral with the trip device and a cooperating means integral with the breaker closure.

A further object of my invention is to provide an improved rating indicating means for use with electrical apparatus, in general.

These and other objects of my invention will be made more apparent from the following description of the structural features and the mode of operation of aA circuit breaker embodying the principles of my invention.

Referring to the drawings:

Figure 1 is a plan view of a two-pole circuit breaker embodying the principal features of my invention;

Fig. 2 is a plan view of the circuit breaker 5 shown in Fig. l'with the cover removed;

Fig. 3 is a sectional view taken on the line III-III of Fig. l;

Fig. 4 is an enlarged perspective-view of the removable trip device used in the circuit breaker 10 shown in Figs. 1 to 3; and

Fig. 5 is an enlarged exploded perspective view of the trip device shown in Fig. 4.

The circuit breaker used in this preferred embodiment of my invention, which is a two pole 15 double break circuit breaker, comprises, generally, a base I of molded insulating material upon which the various structural features of the device are mounted, two stationary contact assemblages 3 and 5, a pair of moving contacts l and 9 20 for cooperating therewith to open and to close the electrical circuit through the breaker, an operating mechanism il for moving the circuit breaker contacts to the open and to the closed circuit positions, and a removable trip device i3 25 which cooperates with the operating mechanism Il to cause the circuit to be opened upon the occurrence of predetermined conditions. The molded base l is provided with four upstanding side portions l5 which are adapted to cooperate 30 with the removable cover ll--likewise of molded insulated material--to completely enclose the circuit breaker mechanism and the trip device.

A cap screw I9 is provided for positioning and retaining the cover i'l of the breaker in the posi- 35 tion shown in Figs. l and 3. The cover is also provided with an opening 2l for cooperating with the rating indicating means of the trip device, as will be described in detail in a subsequent paragraph. 40

A pair of terminal members 23 and 25 are affixed to a suitable support 21 molded in the base l by means of two screws 29. These screws 29 also serve to support the upper iiexible members 3i and 33 of the stationary contact assemblages 3 45 and 5, which project outwardly from the support 21. Two similar contact members 35 and 31 (Fig.

3) are positioned near the lower portion of the molded base l, being aiiixed thereto by means of suitable screws (not shown). The flexible con- 50 tact member 35 is connected to a third terminal 39 by a conducting strip 4I and a-cylindrical tube 43 of conducting material which is molded into the base itself, the screw 45 serving to connect the conducting strip 4| with the tubular conduct- 55 ing member 43. The interior of the tubular ccnducting member 43 is threaded thereby providing a means for engaging the screw 45 and the screw 41 which is used for connecting one of the conductors to the terminal 39. The flexible stationary contact member 31 is connected to a second tubular conducting means 43 by means of a conducting strip 49 and a screw 5|. The ltwo pairs of exible stationary contact members (3| and 35, and 33 and 31) are each adapted to be bridged by one of the cylindrical moving contacts 1 and 9. The contacts 1 and 9 are supported for movement into and out of engagement with the stationary contact assemblages 3 and 5, and are insulated from each other, by the support member 53.

'Ihe second tubular conducting member 43 is adapted to be connected to the main frame 55 of the trip device i3 by means of a screw 51 which engages a suitable hole 59 in the frame. The frame 55 is connected, in turn, to one end of one of the thermally responsive, bimetallic trip elements 6| by means of a rivet 62 (Fig. 5), and is adapted to support the other bimetallic trip element 6| and the terminal 53 through the engagement of the other rivet 62 with the hole 65 therein. The other bimetallic trip element is electrically connected to the terminal member |53 by the associated rivet 52 but both these elements are insulated from the main frame 55 by the insulating member t1 which is interposed therebetween. The terminal member t3 is adapted to be electrically connected to a third tubular conducting member 53 molded in the base by means of a screw 53 which engages a suitable threaded opening therein. This third tubular conducting member @t is in turn connected to the fourth terminal li of the circuit breaker through the agency of a third conducting strip it, which is electrically connected to the member @Si and to the terminal li by screws lid and i5. Suitable openings |71 and 'it are provided in the base i for permitting the passage therethrough of the line conductors.

The trip device is shown particularly in Figs. e and 5, and, as mentioned above, is adapted to be entirely supported upon the frame member 55. The thermally responsive bimetallic trip elements 5| are rigidly connected together at one end by means of a pair of insulating members Si, a pair of rivets 83, a retaining plate |35, and a latch plate Si. The rivets t3 extend through suitable openings 39 in the ends of the bimetallic elements to engage the retaining plate 35 and the latch plate t1 the spacing of the openings 33 being such that the rivets do not electrically contact the two bimetallic trip elements. A conducting heater 9|, one terminal of which is adapted to be connected to each of the bimetallic trip elements 3| is provided for securing the desired electro-responsive characteristic, the two rivets 93 completing the electrical connections. A mica plate 95 is interposed between the thermally responsive trip elements 5| and the heater 9| in order to increase the time delay upon the occurrence of moderate overloads, and also to prevent the short circuiting of the heater due to possible distortion which might result from the flow therethrough of large overload currents.

, The electrical circuit through the breaker is comparatively direct: Beginning with the terminal 23, the current ilows successively through the exible-stationary contact member 3|, the moving contact 1, the' exible stationary contact member 35, and thence through the conducting strip 4| and the tubular conducting member 43 to the terminal 39. For the other pole, the current flows successively throughthe terminal, the flexible stationary contact member 33, the moving contact 9, the iiexible stationary contact 5 member 31, the conducting strip 49 the second tubular conducting means 43, the frame 55 of the trip device, the left-hand (Fig. 3) blmetallic trip element 6 the heater 9|, the right-hand bimetallic trip element 6I, the terminal member 63, the 10 third tubular conducting member 68, the third conducting strip 13, and thence through the screw 15 to the fourth terminal 1|. Two serially connected breaks are thus provided for each pole.

In the embodiment illustrated, a trip device 15 is provided for only one of the poles of a breaker, This is an optional arrangement, however, as a trip device may be provided for both oi the poles if desired.

The operating mechanism for moving the 20 contacts from the open to the closed circuit position is not an important part of my invention, and any arrangement which is capable of accomplishing this, and which will move the contacts to the open circuit position upon the actuation of the 25 trip device i3, may be used. In the structure shown, the moving contacts 1 and 9 are carried on the support member 53 which is pivoted at the point 95 on a movable cradle 91. 'Ime cradle @1, in turn, is pivoted on the frame 93, of the oper- 30 ating mechanism, by means of a pivot pin ii and is provided with a roller |33 for engaging the projection |05 (Fig. 2) which extends outwardiy from the latch plate 3l of the trip device. The operating handle |91 has a knob portion |39 that 35 is disposed outside the circuit breaker closure and is likewise pivoted on the frame Q3. mi overcenter spring iii operatively interconnects the handle |31 and the movable contact carrying member The breaker is shown in normal open circuit position in Fig. 2. To close the contacts manually, the operating handle |31 is moved toward the right, This movement shifts the line of action of the over-center spring i ii across the c5 pivot point 9S of the contact support member and causes the moving contacts i and il to be moved to the closed circuit position with a snap action. The opening operation is essentially the reverse of this, the handle im being moved in to the direction of the trip device i3. The contacts are opened and are closed with a snap action in order to facilitate the extinction oi. the arc formed incident to the interruption of the controlled circuit. Upon the occurrence of an over- 55 load, the thermally responsive bimetallic trip elements 5| are heated, partly by the current iiow therethrough and partly by the heater 9|, and bend in a direction away from the operating mechanism ii. This movement causes the latch 60 projection |05 to disengage the roller |03 forming a part of the cradle 31, and the operating mechanism then automatically moves the contacts 1 and 9 from the closed circuit position to the open circuit position with a snap action. Fol- 65 lowing the opening of the circuit as a result of the actuation of the trip device 3, the breaker mechanism may be reset by moving the operating handle |01 to the extreme oi position whereupon the cradle retaining roller |03 re-engages the 70 latch projection |05 of the trip device I3.

The terminal portion 63 of the trip device I3 is provided with an upstanding cylindrical member I|3 of insulating material which is adapted to cooperate with the opening 2| in the cover I1. 75

- vices for altering the rating thereof.

The surface o! the cylindrical member III which is visible from the outside of the breaker closure when the cover I1 is in place is provided with some means, such as the numeral illustrated in Figs. 1 and 2 for indicating the current rating of the associated trip device. This arrangement permits the rating of the trip device within the breaker to be ascertained without having to remove the cover I1 and is one of the most important features of my invention.

As shown particularly in Fig. 3, the upstanding cylindrical member I I3 not only serves to provide an indicating means whereby the rating of the trip device may be seen from without the circuit breaker closure, but in addition it serves to substantially close the opening v2| in the closure when the trip device is in an operative position therein. This cooperation of the rating indicating means for the trip device and the closure itself eliminates any necessity for the provision of a transparent covering for the window or like means which permits visual inspection of the indicating means from without the closure, and, moreover, in so doing it does not leave any substantial opening in the closure through which dust might get into the breaker. Furthermore, this arrangement permits the trip device to be removed andreplaced with another of like or dierent rating without requiring any change in lettering on the closure or the substitution of a new name plate in order to preserve the accuracy of the rating indicating means.

I have shown an engraved numeral and letter in combination with the cylindrical member I I3 for visually indicating the rating of the trip device. It is within the province of my invention, however, that the surface of the member I I3 which is visible from the outside of the closure could be colored to indicate a particular rating. Also, the lettering or color on the visible surface oi the member I I3 may cooperate with suitable identifying lettering or the like lplaced on the surface of the closure itself.

It will thus be seen that I have provided a new and improved means for readily indicating to the operator of a circuit breaker the rating of the trip device then disposed therein. In addition, I have disclosed an improved rating indicating means particularly adaptable for use with circuit breakers utilizing interchangeable trip de- My improved means permits the visual determination of the rating of the trip. device from without the breaker closure without necessitating the use of transparent coverings for the windows or other similar means which permit such visual determination, and at the same time, it permits the breaker closure to be substantially closed when the trip device is in an operative position therein. Further, I have shown how an improved indicating means, according to the objects of my invention, may be used with a circuit breaker without having to change any of the lettering on the outside of the closure when the trip device itself is changed.

While, in accordance with the patent statutes, I have disclosed an embodiment of my invention as applied to a particular structure, it is to be understood that the details of this embodiment are merely illustrative and that variations in their precise form will be both desirable and necessary in many applications. I desire, therefore, that the language of the accompanying claims shall be accorded the broadest reasonable construction and that my invention be limited only by what is explicity stated in the claims and by the prior art. l

I claim as my invention:

1. In combination in a circuit interrupter, a closure, movable means disposed within said 5 closure for opening and for closing the circuit, and a thermally responsive device, likewise disposed within said closure, for causing said movable means to open the circuit upon the occurrence of predetermined conditions, said thermally responsive device being removable from said closure without removing said movable means for opening and for closing the circuit and including means for visually indicating the rating thereof, said closure including means permitting said rating indicating means to be visible from the outside of said closure.

2. In combination in a circuit interruptor, a closure, movable means disposed within said closure for opening and for closing the circula-20 and a trip device, likewise disposed within said closure, for causing said movable means to open the circuit upon the occurrence of predetermined conditions, said trip device being removable from said closure Without removing said movable g5 means for opening and for closing the circuit and including means for visually indicating the rating thereof, said closure including means permitting said rating indicating means to be visible from the outside of said closure.

3. In combination in a circuit interrupter, a closure, movable switching means disposed within said closure for opening and for closing the circuit, and a current responsive device, likewise disposed Within said closure, for causing said 35 movable means to open the circuit upon the occurrence of predetermined conditions, said current responsive device being entirely removable as a unit from said closure, without necessitating the removal of said movable switching means, to permit the substitution therefor of similar devices and including means for indicating the rating thereot, said closure including means permitting said rating indicating means to be visibleirom the outside of said closure,

4.'In combination in a circuit interruptor, a closure, movable switching means disposed within said closure for opening and for closing the circuit, actuating means for said switching means, and-a current-carrying trip device, likewise disposed Within said closure, for causing said actuating means to move said switching means to the open circuit position upon the occurrence of predetermined conditions, said trip device being removable from said closure `evith- 5 out removing said actuating means and including means for visually indicating the current rating thereof, said closure including means permitting said rating means to be visible from the outside of said closure.

5. In electrical apparatus, a closure having an opening therein, and an electro-responsive device, disposed within said closure, for actuating said apparatus, said electro-responsive device being entirely removable as a unit from said closure, and having means formed integral therewith for substantially closing the opening in said closure and for visually indicating the rating of said electro-responsive device when said device is in an operative position within said 'o closure.

6. In electrical apparatus, a closure having an opening therein, and an electro-responsive device disposed Within said closure for actuating said apparatus, said electro-responsive device being entirely removable as a unit from said closure to p'ermit the substitution therefor oi similar unitary devices and including means, forming an integral part thereof, which extends into and thereby substantially closes the opening in said closure when said device is in an operative position therein, said closing means including means visible from the outside of said closure for indicating the rating of said electroresponsive device.

7. In electrical apparatus, a closure having an opening therein, and a thermally responsive device disposed within said closure for actuating said apparatus, said thermally responsive device being entirely removable as a unit from said closure to permit the substitution therefor of similar unitary devices and including means, forming an integral part thereof, which extends into and thereby substantially closes the opening in said closure when said device is in an operative position therein, said closing means including means visible from the outside of said closure i'or indicating the rating of said thermally responsive device.

8.111 electrical apparatus, switching means, actuating means for said switching means, an electro-responsive device for causing said actuating means to move said switching means to the open circuit position upon the occurrence oi predetermined conditions, and a closure, having an opening therein, for said interruptor, said electro-responsive device being removable as a unit from said closure, without necessitating the removal oi said switching means or said actuating means, to permit the substitution therefor of similarly dimensioned devices in order to change the rating of said interruptor, and' including means visible from the outside of said closure for closing said opening and for indicating the rating oi the electro-responsive device then within the closure.

9. lin electrical apparatus, a closure having an opening therein, and a thermally responsive device disposed vfithin said closure for actuating said apparatus, said thermally responsive device including meansliormed integral therewith, which extends into and thereby substantially closes said opening when said thermally responsive device is in an operation position therein, said closing means including means visible from the outside of said closure for indicating the rating of said thermally responsive device.

l0. In a circuit intersupter, separable contact means, a closure having an opening therein, and a thermally responsive means disposed within said closure, for causing said separable contact means to open the controlled circuit upon the occurrence of predetermined conditions, said thermally responsive means being removable from said closure without removing said separable contact means and including means, which extends into and is visible from the outside of said closure for substantially closing said opening and for indicating the rating of said thermally responsive means.

l1. In a circuit interrupter, movable switching means, actuating means for said switching means, a closure having an opening therein, and an electro-responsive means, disposed within said closure, for causing said actuating means to move said switching means to the open circuit position upon the occurrence of predetermined conditions, said electro-responsive means being removable from said closure without removing said actuating means and including means, which extends into and is visible from the outside of said cloaoe'mei sure for substantially closing said opening and for indicating the rating of said electro-responsive means.

12. In a circuit interrupter, movable switching means, actuating means for said switching means, 5 a closure having an opening therein, and a current-carrymg trip device, disposed within said closure for causing said actuating means to move said switching means to the open circuit position upon the occurrence of predetermined conditions, l said trip device being removable from said closure without removing said actuating means or said switching means and including means which extends into and is visible from the outside of said closure for closing said opening and for indil eating the current-rating of the trip device then within said closure.

13. In a circuit interruptor, separable. contact means, actuating means for said contact means, a

closure having an opening therein, and a current carrying trip device, disposed within said closure for causing said interrupter to open the controlled circuit upon the occurrence of predetermined conditions, said trip device being removable as a unit from said closure, without necessitating the removal oi said switching means or said actuating means, to permit the substitution therefor of simlarly dimensione'd devices in order to change the current rating of said interrupter, said trip device including means which extends into and thereby closes said opening when said trip device is in an operative position therein, said closing means being provided with means, visible from the outside of said closure, for indicating the current rating of the trip device then within the closure.

14. In a circuit interrupter, a base, separable contacts and an actuating means therefor fixedly mounted on said base, an electro-responsive trip device releasably mounted on said base, and a cli removable cover means adapted to cooperate with said base in such manner that the working parts o said interruptor may be substantially completely enclosed, said electro-responsive trip device being removable es a unit from operative engagement with said actuating means without necessitating the removal of said actuating means, 'when said cover is removed from said base, to permit the substitution therefor of similarly dimensioned trip devices in order to change the rating of said interrupter, said cover means having an openingv therein and said trip device including means,. which extends into and thereby closes said opening when said trip device operatively engages said actuating means and said cover is in place, said closing means including means visible from the outside of said cover for indicating the current rating of the associated trip device.

15. In electrical apparatus, a base member, a cover means for cooperating therewith .to provide a closure for said apparatus, and a removable, current carrying trip device for effecting the operation of said apparatus upon the occurrence of predetermined conditions, said trip device including a pair of rigid terminal members, which are adapted to engage said base member and upon which the other elements of said device are supported, current-carrying electro-responsive means electrically connecting said terminals, and an outwardly projecting member which is rigidly supported, upon one of said terminal members, said closure having an opening therein and said outwardly projecting member being adapted to extend into and thereby close said opening when said trip device is operatively positioned within 7i said closure, said projecting means including means visible from the outside o! said closure for indicating the current rating of the associated trip device.

16. In electrical apparatus, a base member, a cover means for cooperating therewith to provide a closure for said apparatus, and a removable, current carrying trip device for effecting the operation of said apparatus upon the occurrence of predetermined conditions, said trip device including a pair of rigid terminal members, which are adapted to engage said base member and upon which the other elements of said device are supported, insulating means for mechanically con- 15 necting said terminal members in order to impart greater rigidity to said trip device, current-carrying electro-responsive means electrically connected across said terminals, and an outwardly projecting member of insulating material which is rigidly supported upon one of said terminal members, said cover having an opening therein and said outwardly projecting member being adapted to extend into and thereby close said opening when said trip device is operatively positioned within said closure, said projecting means 10 including means visible from the outside of said closure for indicating the current rating of the associated trip device.

ROBERT M. DAVIS. 

